Application of platelet derived growth factor (PDGF) for activating hair follicles is disclosed, which is to introduce the PDGF solution into scalp to activate the hair follicles and increase the volume of hair. By introducing the PDGF, the stem cells of hair follicles can be activated so that the hair follicles in telogen are able to re-enter into anagen phase and re-grow hair.本發明係提供一種血小板衍生生長因子用於活化毛囊之用途,其係將血小板衍生生長因子溶液導入頭皮中,以活化毛囊及增加髮量。藉由血小板衍生生長因子的導入,可激活毛囊幹細胞,使處於休止期中毛囊,重新進入生長期再度生髮。